I've seen some NES and GB/GBA emulators and I think there was even some 3D console compiled via emscripten. But "HTML5" does not guarantee WebWorkers and WebGL support which is the very very least it would probably need. I'm also dubious on whether the browser supports enough "local storage" for any commercial game. But as always, if someone is interested in doing it, "patches welcome" (or is the modern version "pull requests" welcome?).

There would be significant challenges. Probably would envy JPCSP's performance, but then who knows. Also, it would be more like a complete rewrite than a port.

But, it would likely not be much of a port. Here are the things that would be entirely useless from the current PPSSPP:

* The jit. Maybe you could write one that outputs js and hope the js engine jits it in some reasonable way.
* Memory handling. There's no way our fast way of accessing memory could be used - it'd have to be slow.
* ATRAC3+ support. This would be its own unique challenge. Rewrite FFMPEG in js too?
* Video support in general. It would have to be done totally differently, if it could work at all.
* Portability. It would have its own issues and browser compatibility, so that would start from scratch.

Other than that, with *significant* investment of time, it could be possible. I'm certainly not interested.

There would be significant challenges. Probably would envy JPCSP's performance, but then who knows. Also, it would be more like a complete rewrite than a port.

But, it would likely not be much of a port. Here are the things that would be entirely useless from the current PPSSPP:

* The jit. Maybe you could write one that outputs js and hope the js engine jits it in some reasonable way.
* Memory handling. There's no way our fast way of accessing memory could be used - it'd have to be slow.
* ATRAC3+ support. This would be its own unique challenge. Rewrite FFMPEG in js too?
* Video support in general. It would have to be done totally differently, if it could work at all.
* Portability. It would have its own issues and browser compatibility, so that would start from scratch.

Other than that, with *significant* investment of time, it could be possible. I'm certainly not interested.

Such an old thread, and we had html5/javascript psp emu sitting from a long time here github.com/jspspemu/jspspemu it run simple games, with a little more attention until now it would have nice compatibility, speed too.
Below on the site are three working games/samples. Two links on top github page lead to atual emu and blog, that explains everything.